Patent GB-1176567-A (GB)
Title: Apparatus for Welding Parts to Workpieces
IPC: B23K9/20
Filed: 1967-07-06
Abstract: 1,176,567. Welding by pressure. GREGORY INDUSTRIES Inc. 6 July, 1967 [8 July, 1966], No. 31204/67. Heading B3R. Apparatus for welding a part to a workpiece comprises a welding tool including a body, a chuck leg longitudinally movable in the body, means for urging one end of the leg out of the body towards the workpiece, a chuck connected to the one end of the leg, means for moving the body between a first position remote from the workpiece and a second position in which a part carried by the chuck engages the workpiece, means for retracting the leg and chuck when the body is in the second position, means to plunge the leg and chuck back towards the workpiece a part carrying supply member and means for guiding the supply member between a part receiving position remote from the chuck and a part supplying position adjacent the chuck. An apparatus for welding opening tabs to scored can lids comprises a conveyer 22, Fig. 1 for moving the can lids 20 at 250-300 per minute beneath a welding tool 36. Tabs 24 having reinforcing ribs and projections 26, Fig. 2, are welded by the projections to the lids. The apparatus also includes a drive motor 30, a speed control 32, a mechanical welding controller 34 and a feeding device 38. The tool 36 includes a housing 40, Fig. 5, slidably carrying an electrode 72 connected to one terminal of an electric power supply and a chuck leg 42 connected to the other terminal of the supply. The electrode and leg are urged downwardly by springs and are arranged to engage the workpiece and tab respectively. A lifting link 64 on the top of the leg 42 connects the leg to a lifting pin 66 to retract the leg from the workpiece during welding. A chuck 62 on the leg 42 has a magnet to retain a tab in an open groove in the chuck and an arm 108 pivotally mounted and spring-urged at one end of the groove. The chuck also has insulating inserts to prevent current flow therethrough if the chuck is lowered without a tab in the chuck. The tabs 24 are stacked in a vertical passage 124 in a block 118 and a slide 122 is arranged horizontally in a passage 120 beneath the passage 124, the slide having an offset portion to receive a tab and carry it to the groove in the chuck as it moves in the passage 120. The slide 122 is connected by linkage to a feed drive shaft 206 connected by linkage to a cam follower lever 212 carrying a cam follower 216 spring-urged against a feed cam. A spring- urged rod 146 acts through linkage 142, 134 to urge the welding tool 36 upwardly; and a further linkage acting through a lever 136 from a further cam is provided to move the tool 36 downwardly. An adjustable screw 180 engages the pin 66 when the tool 36 is in its lower position and the screw is operated through linkage by another cam to lift the chuck 62 relatively to the tool 36. This other cam allows the screw to drop suddenly to permit the chuck to be rapidly returned. The current supply to the parts to be welded is effected by rotation of a current conducting sector on the main drive shaft relatively to contacts. In operation with the chuck 62 initially raised and the slide 122 in its rear position the slide is caused to move forwardly to carry a tab from the bottom of the stack to a position in the chuck, the tool 36 is then caused to move downwardly and although the tool remains vertical it moves in an arcuate path so that the projection 26 on the tab slides slightly across the can lid. The electrode 88 engages the lid at this time. Contacts are made immediately prior to the lifting of the arm 66 by the screw 180 to cause a pilot arc to be struck, followed by the main arc and then the tab 24 is plunged back into contact with the lid to effect a weld. The tool 36 is then raised and the welded parts are left on the conveyer, the magnet in the chuck having been overcome. A capacitor power source may be used.